Ink jet recording device having staggered recording element arrays

ABSTRACT

An ink jet recording device has a recording head with a first array of ink discharge ports for emitting a first ink and a second array of ink discharge ports arranged for emitting a second ink, the first and second inks being of different colors, a main scanning element for moving the recording head relative to a recording medium for a main scanning during an emission of the inks by the recording head, and a subsidiary scanning element for moving the recording head relative to the recording medium by a predetermined subsidiary scanning distance during a non-ink-emission by the recording head. The first and second arrays of ink discharge ports are arranged with a separation between arrays that is not less than the predetermined subsidiary scanning distance in the direction by the subsidiary scanning element.

This application is a division of application Ser. No. 08/360,121 filedDec. 20, 1994, which was a continuation of application Ser. No.07/921,462 filed Jul. 28, 1992, which was a continuation of applicationSer. No. 07/671,147 filed Mar. 18, 1991, which was a continuation ofapplication Ser. No. 07/470, 775 filed Jan. 26, 1990, all now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an ink jet recording method and a color inkjet recording device which are applied to copying machines, facsimiles,printers for image processing, and other printers in general. Moreparticularly, it pertains to a scanning type ink jet recording deviceequipped with a plural number of recording heads having a plural numberof discharge ports arrayed in the sub-scanning direction and to arecording method of said device.

2. Related Background Art

In the prior art, for improvement of gradation or density of recordedimages, it has been practiced to form a plural number of pictureelements for forming the image on a recording medium with a pluralnumber of overlapping ink droplets, or for improvement of adjacentpicture element densities, to shoot a plural number of ink droplets at ahigh density.

When this is applied to color, there is the advantage that colorreproducibility can be improved.

Further, in the case when the recording medium is a transparent film fortransmission type OHP (overhead projector), etc., the image recordedthereon is required to be increased in transmission density as a whole,and also in this case the above system is effective.

In these systems, emission of ink droplets for emitting a plurality ofink droplets on one picture element is performed by scanning of therecording head for plural times while the recording medium is fixed assuch. Accordingly, scanning for plural times corresponding to higherdensification or scanning for plural times corresponding to the inkcolors to be mixed is required for the recording range per one scanningin scanning type recording, and no high speed recording can bepracticed. In other words, if a high density image or a color image isformed for ordinary printing, a printing time is required which is aslong as 2-fold to 4-fold of the time required for ordinary printing.

Accordingly, for the purpose of making faster even by little therecording speed, in order to increase the recording range per onescanning, it is effective to enlarge the recording head by formation ofa multi-nozzle, but since it is limited to make the head lengthy, theratio of shortening of the printing time is little in scanning type inkjet recording.

In contrast, U.S. Pat. No. 4,320,406 discloses a constitution whichminiaturizes the head constitution itself of a color device by dividingthe nozzles (discharge port) of the single recording head itself formedinto a multi-nozzle into four nozzle units predetermined for differentinks, but since the recording speed depends on only one recording head,the ink discharge range of one color is reduced to great extent, wherebythe advantage of the recording formed into a multi-nozzle will be lost.

The present inventors have investigated about the prior art and foundthe following problems.

When image density is enhanced or color formation is effected byscanning for plural times continuously for the recording range to berecorded by one scanning, because the picture element is formed by inkdischarge for plural times, the ink amount per one picture elementbecomes larger, and therefore in the case of recording medium of whichink receptive amount is limited such as film for OHP or one having poorink absorptivity, the amount or the rate of ink absorption is limited,whereby ink may be sometimes overflowed from the picture element,resulting in deterioration of the image quality.

Particularly, a plural number of recording heads corresponding to therespective inks had a constitution arranged in the scanning direction,and therefore in the case when different inks were overlapped, theemission density per unit time became greater, whereby the above problemof ink overflow became marked.

Generally speaking, recording papers with increased ink absorptionamount have been known, and recording is possible only on expensive andspecific converted papers and only for limited recording. However, whenusers employ another paper or sheet, defective recording may be broughtabout, and in the worst case, users sometimes judged that the recordinghead was defective to make the recording head useless.

Anyway, even by use of a multi-nozzle head, because scanning isperformed for plural times by stopping of paper feeding of the recordingmedium, the recording speed cannot be lowered, and also, when only arecording medium excellent ink absorptivity is used, the disadvantagesof the users by limitation of the recording will be brought about, suchas the disadvantage of failing to use a diversity of recording media.

Further, as the problem of fixability, boundary region, the followingfacts have been found out, and it has been found that the difference inrecording characteristics becomes marked when using different recordingmedia.

More specifically, a great difference in ink absorption ability occursat the boundary portion of the scanning line in overlapped recording,whereby density irregularity due to nonuniform ink absorption is liableto be generated.

Also, in the constitution which performs recording for plural times onthe same picture element through the same discharge port, irregularityin density and shooting precision between the discharge ports may besometimes intensified to lower the picture element.

Further, since the ink densities change at the same time over the wholeregion of the width of the discharge port (scanning region), andtherefore stretching and shrinkage of the recording medium accompaniedwith ink absorption will occur at the same time, whereby the changeamount becomes greater.

On the other hand, divided recording is a system which is to be used fora recording medium inferior in absorption characteristic, and even afterthe final scanning (ink emission), the recorded surface cannot betouched before elapse of a certain time. Therefore, the members such asdischarge rollers, press rollers, etc. are required to be departed fromthe above-mentioned recording region by the head width or more, wherebyenlargement of the device or lowering in paper feeding precision may bebrought about.

Further, the problem of stretching and shrinkage of the recording mediumas mentioned above also occurs in divided recording.

SUMMARY OF THE INVENTION

The present invention is intended to provide an ideal ink jet recordingdevice which has solved the problems as described above in the case ofusing a plural number of recording heads equipped with a plural numberof discharge ports (also called multi-nozzle head).

An object of this invention concerns an ink jet recording device havinga recording head with a first array of ink discharge ports for emittinga first ink and a second array of ink discharge ports arranged foremitting a second ink, the first and second inks being of differentcolors, a main scanning means for moving the recording head relative toa recording medium for a main scanning during an emission of the inks bythe recording head, and a subsidiary scanning means for moving therecording head relative to the recording medium by a predeterminedsubsidiary scanning distance during a non-ink-emission by the recordinghead. The first and second arrays of ink discharge ports are arrangedwith a separation between arrays that is not less than the predeterminedsubsidiary scanning distance in the direction by the subsidiary scanningmeans.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side sectional view of the ink jet recording deviceaccording to a first embodiment of the present invention;

FIG. 2 is a block diagram showing the control constitution according torecording of the device shown in FIG. 1;

FIGS. 3A and 3B are conceptional views of the recording method in thefirst embodiment;

FIG. 4 is a graph showing the ink absorption characteristics of therecording medium;

FIG. 5 is an illustration showing the image evaluations corresponding tothe ink densities of the recording medium;

FIG. 6 is an illustration of image blotting of FIG. 6A and FIG. 6B;

FIG. 7 is an illustration of overlapping of inks in the embodiment ofthe present invention;

FIG. 8 is a perspective view showing an ink jet cartridge of 4 headsintegrated in the second embodiment of the present invention;

FIG. 9A and FIG. 9B are conceptional views of the recording method inthe second embodiment;

FIG. 10 is a perspective view of the ink jet recording device accordingto the second embodiment of the present invention;

FIGS. 11A and 11B are conceptional views of the recording method in thethird embodiment of the present invention;

FIG. 12 is a side sectional view of the ink jet recording deviceaccording to the fourth embodiment of the present invention;

FIG. 13 is a block diagram showing the control constitution according torecording of the device shown in FIG. 12;

FIG. 14A and FIG. 14B are conceptional views of the recording method inthe fourth embodiment;

FIG. 15A and FIG. 15B are conceptional views showing the recording modeof the prior art, which is applicable to the seventh embodiment of thepresent invention;

FIG. 16 is a perspective view showing the ink jet cartridge of 4 headsintegrated in the fifth embodiment;

FIG. 17A and FIG. 17B are conceptional views of the recording method inthe fifth embodiment;

FIG. 18 is a perspective view of the ink jet recording device accordingto the fifth embodiment of the present invention;

FIG. 19 is a conceptional view of the recording method in the sixthembodiment of the present invention;

FIG. 20 is a schematic illustration of the pertinent portion of theseventh embodiment of the present invention;

FIG. 21 is a schematic illustration of the pertinent portion of theoperation panel to be used in the seventh embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, the embodiments of the present inventionare described in detail.

FIG. 1 is a side sectional view showing the principal portion of the inkjet recording device according to an embodiment of the presentinvention. In the Figures, 1 to 4 are recording heads each having 64 inkdischarge ports, and the ink passage communicated to these dischargeports has an electrothermal transducer for generating energy fordischarging ink arranged therein. Also, the recording heads 1, 2, 3 and4 are recording heads for discharging respectively inks of red (R),green (G), blue (B) and black (B), and they are repsectively held on thecarriage 5. With such arrangement, the directions of the discharge portarray in the respective recording heads forms the sub-scanning directionas described below with reference to FIG. 3A, and they are arrayed sothat the recording region by scanning may be the same.

The carriage 5 is engaged slidably with a pair of guide shafts and isalso movable in the scanning direction (the direction perpendicular tothe drawing) by the carriage motor as described below.

The recording heads 1 to 4 are connected electrically through thecarriage to the main control section as described below with referenceto FIG. 2, and otherwise connected to the ink tanks of the respectivecolors at the ink tank portion 7 by the ink tube bundle 6 correspondingflexibly to the movement of the carriage 5 so that ink supply can bedone. On the other hand, the recording medium 8 is conveyed by theconveying roller pair 9 through the paper feeding guide 10 at apredetermined timing successively in the arrowhead direction in the FIG.to the recording portion. At the recording portion, the recording medium8 is adsorbed through the electrostatic attracting force of theadsorption conveying belt 11, and adsorption supporting conveying isdone while being synchronized with the conveying roller pair 9 withmovement of the belt 11, and the medium stops successively atpredetermined positions to perform recording.

FIG. 2 is a block diagram showing the recording control in the ink jetrecording device shown in FIG. 1. In the same Figure, 5A is the carriagemotor for driving the carriage 5 through a carriage driving mechanismsuch as belt, pooley, etc., and 20 is the head driver for generatingdischarge signals for the respective discharge ports based on therecording data supplied from the control section. 30 is the paperfeeding driving section for driving the conveying roller 9 and theadsorption conveying belt 11, and is constituted mainly of a motor, etc.

The control section shown in the Figure has CPU 100 which practicesprocessing according to control of the device while performing givingand receiving of the data between the host device or the respectivesections of the recording device, RAM100A which becomes the work area inprocessing of CPU100, and ROM100B which memorizes the processingprocedure such as recording actuation, etc. as shown in FIG. 3A and FIG.3B.

FIGS. 3A and 3B are conceptional views for illustration of the recordingmethod in the embodiment shown in FIG. 1. In FIG. 3A, the recordingheads 1 to 4 for discharging respectively the inks of the respectivecolors of R, G, B and K are, as mentioned above, supported and fixed sothat the respective discharge port arrays 3 may become perpendicular tothe scanning direction (sub-scanning direction) relative to the bothsurfaces of the head supporting is portion 12.

In the same Figure, the discharge port array 13 cannot be seen as it is,but the recording head is shown as perspective from the rear thereof.More specifically, the array is made so that the widths of the dischargeport arrays of the recording head (in the Figure, RL=GL=BL=KL) may beconnected to one another without gap, and the respective recordingregions (R, G, B, K) by one scanning becomes continuous with the samewidth. When the recording medium is conveyed as described above to therecording regions (R, G, B, K), the carriage 5 scans to initiaterecording.

The recording medium 8 stops at the position of (the first scanning) inFIG. 3A by the conveying roller pair 9 and the adsorption conveying belt11. This position is under the state where the tip portion of therecording medium 8 is in the recording region K, and the recordingmedium has not reached other recording regions R, G, B. Therefore, inthe first head scanning, recording is performed only with the K head.

After the first scanning, the recording medium 8 is again conveyed bythe conveying roller pair 9 and the adsorption conveying belt 11. As isapparent from FIG. 3A, the conveying distance PL is set the same as thewidth(RL, GL, BL, KL) of the discharge port array. In the secondscanning, the region recorded in response to the recording signal K₁ bythe head 4 of K ink in the first scanning has moved to the B recordingregion, and recording is performed in response to the recording signalB₁ with the head 3 of B ink.

On the other hand, at the portion conveyed newly to the K recordingregion, recording is performed in response to the next recording signalK₂ with the head 4 of K ink. Here, since the recording medium 8 has notyet reached the R and G recording regions, still no recording isperformed with the head 1 of R ink and the head of G ink.

After the second scanning, the recording medium is again conveyed by thePL width. In the third scanning, at the portion where recording wasperformed with the recording signals of B₁ and K₁, recording in responseto the recording signal G₁ is done. At the portion where recording wasperformed with the recording signal K₂₁, recording is done in responseto the recording signal B₂ with the head 3 of B ink. Also, at the Krecording region, the recording signal K₃ is recorded with the head 4 ofK ink.

After the third scanning, the recording medium is similarly conveyed bythe Pl width and the fourth scanning is performed. In the fourthscanning, is at the portion where recording was performed in response tothe recording signals of K1, B1, G1, recording is done in response tothe recording signal R1with the head 1 of R ink. Thus, the recordingmedium is successively recorded at every PL width with inks of black,blue, green and red colors.

FIG. 3B shows the recording signals of the respective heads for everyhead scanning when recording of A4 size is performed with the recordinghead of this embodiment, and at the rear end of the recording medium,the recording signals are successively lost from the K head. Aftercompletion of recording of the final scanning, the recording medium 8 isdischarged out of the machine.

Whereas, FIG. 4 shows the ink absorption characteristics of recordingmedia, with square root of absorption time (√S) being shown on the axisof abscissa, and absorption amount of ink (aqueous) (nl/mm²) on the axisof ordinate. It can be understood that, in the coated paper having anink receptive layer provided on the surface layer, a large amount of inkcan be absorbed within a short time, while in the non-coated paper usedin this embodiment, initial absorption is low and a long time isrequired for absorption of ink.

FIG. 5 shows the results of examination of blotting degree of imageswhen inks of two colors are emitted onto the recording mediumsubstantially simultaneously (sharpness of the boundary portion betweenthe inks of two colors) in Table. In this Table, the mark ∘ shows onewhich is judged as practically useful, the mark Δ one which is slightlyinferior in image quality and the mark x one which is entirelypractically unuseful.

From this experiment, it can be seen that the ink amount which can berecorded within a short time is 20 nl/mm² or less in the non-coatedpaper and 25 nl/mm² or less in the coated paper. This phenomenon can beestimated to occur according to the mechanism shown in FIG. 6.

More specifically, the absorption of ink onto paper, as shown in FIG. 6Amay be considered to be effected in the order of contact, collision, dotformation, permeation, drying. As shown in FIG. 4, in the case of thenon-coated paper, in a time of 0.2 √S or shorter, no ink of 11 to 12nl/mm² or more can be absorbed and therefore, if an ink more than thatis emitted substantially simultaneously, the ink will be overflowed and,as shown in FIG. 6B, the overflowed ink is attracted to the adjacent inkwhich has reached previously onto the paper, whereby blotting may beconsidered to occur at the boundary portion.

In contrast, in the present embodiment, since head scanning is performedsuccessively with the recording regions for the respective heads beingseparated in one scanning, blotting at the boundary portion becomessmaller as shown in FIG. 7.

For verifying the effect of this embodiment, the recording test wasperformed under the conditions shown below and consequently goodrecorded images with little blotting at the boundary portion could beobtained. In contrast, when recording was performed simultaneously withthe arrangement of heads being constituted so that the respective headrecording regions were overlapped with each other as in the ink jetrecording device in the prior art, images which were entirelypractically useless were obtained.

To describe in detail, this embodiment can perform recording of 7 colorsby use of 4 colors of R, G, B, K, and recording was performed on arecording medium of A4 size at a recording density of 360 DPI and adriving frequency of 5.4 kHz. For this recording medium, a two-foldpaper on which the diameter of the ink droplet emitted is expanded to2-fold is used.

In this case, because the recording density is 360 DPI, the pictureelement size becomes 70.56 μm square, and the dot diameter embedding thepicture element as a whole becomes 100 μm. Accordingly, the dropletdiameter emitted onto the 2-fold paper becomes 50 μm, namely its volumebecomes 65.5 pl.

When recording is performed under such conditions, the plane density ofmono-color (one discharge) becomes 13.2 nl/mm², and the plane density oftwo colors (two discharges) becomes 26.3 nl/mm², and when two colors areoverlapped or adjoined at the same time as shown in FIG. 5, the imagebecomes bad.

As is apparent from the above description, this embodiment, which hasbeen made to have a constitution excluding overlapping or adjoining oftwo colors within a short time, is also effective for a recording meidumwith poor water absorption as the non-coated paper.

Also, according to the above-mentioned recording conditions, since inthis embodiment the recording region in one scanning is divided into 4,and therefore scanning for 68 times is required for recording of A4size. This means that the scanning times are increased only by 3 ascompared with the device constitution of the prior art, thus resultingin substantially no lowering in recording speed.

In contrast, for recording of the same A4 size, if the recording regionis made the same as in the prior art and the boundary blotting isprevented by overlapping scanning for 4 times at the same position,scanning of 260 times which is 4-fold is required.

Also, for example, in the case of recording only of K ink, the recordingmedium may be discharged without performing the 66th to 68th scanning,and by doing so, there is no lowering in recording speed at all in thecase of mono-color recording.

In the case when the recording medium is a transparent film formed ofPET or PET coated with an water absorptive material, the presentembodiment is also effective.

Further, the present embodiment is effective for obtaining recording ofhigher image quality even in the case of a recording medium having inkabsorptivity such as the coated paper.

FIG. 8 is a perspective view showing the second embodiment of thepresent invention, and this embodiment has a constitution of recordingheads corresponding to recording of full color. That is, it hasrecording heads 1A, 2A, 3A and 4A corresponding to the respective colorsof yellow (Y), magenta (M), black (K) and cyan (C).

Each of these recording heads has 128 discharge ports arrayed in thesub-scanning direction. Also, it is a recording head of the cartridgetype which constitutes integrally the ink tanks of the respectivecolors, and therefore when there is no more ink, the whole recordinghead is exchanged with another cartridge.

When high resolution recording is performed as in this embodiment, thepositional precision between the heads is required to be higher, and byexchange of the head with 4 colors integrated as in the head of thisembodiment, it becomes possible to effect strict registration duringshipment, and even in a device of the head exchange system, high imagequality recording extracting fully the performance of the head isrendered possible.

FIGS. 9A and 9B are conceptional views showing the recording method bythe recording head shown in FIG. 8, which are similar to FIGS. 3A and3B, respectively.

This embodiment shows the constitution in which recording at a recordingdensity of 600 DPI is performed on a 2-fold paper. Thus, since therecording density is 600 DPI, the picture element size 42.33 μm isdetermined, and similarly as described above, the droplet diameterbecomes 30 μm and its volume 14.2 pl.

As the result, the plane density when mono-color, 2 colors, 3 colors and4 colors are emitted overlappingly or adjoiningly become respectively7.9 nl/mm², 15.8 nl/mm², 23.7 nl/mm² and 31.6 nl/mm² Again, as isapparent from FIG. 5, the permissible range where no blotting of inkoccurs in this embodiment is up to 2 colors.

Accordingly, as shown in FIG. 9, it becomes possible that the recordingheads corresponding to 2 colors make the recording regions the same. Inthe case of the same Figure, as shown in FIG. 9A, the recording heads 2Aand 4A of M ink and C ink have the same recording regions as therecording heads 1A and 3A of Y ink and K ink, respectively, andrecording of A3 size is performed by scanning for 77 times in the datamode as shown in FIG. 9B.

FIG. 10 is a perspective view of an ink jet recording device which canmount the recording heads shown in FIG. 8 and FIG. 9, and the carriage 5is engaged slidably with a pair of guide shafts, and makes scanning ofthe recording regions with the recording heads 1A, 2A, 3A, 4A possibleby driving of the carriage motor 5A.

FIGS. 11A and 11B are conceptional views showing the recording methodaccording to the third embodiment of the present invention. As isapparent from FIG. 11A, the recording head of this embodiment has therespective recording heads 1 and 4 corresponding to B ink and K inkarranged in the sub-scanning direction with an interval between theirdischarge port arrays corresponding to the amount of paper feeding.

More specifically, the recording condition in this embodiment is arecording density of 300 DPI, and in this case, the droplet volume inthe same process as in the second embodiment as described above isdetermined as 113 pl. At this time, the plane density of mono-color inkbecomes 15.8 nl/mm² This is, as shown in FIG. 5, the range where noblotting of image occurs even in the case of the non-coated paper, butbecause it is a value approximate to the critical value of blotting,blotting may also sometimes occur.

Therefore, by providing an interval corresponding to the paper feedingamount between the respective recording heads, ink absorption isaccelerated by the time of one scanning and paper feeding. By doing so,ink blotting can be surely cancelled.

The constitution of this embodiment has recording heads each having 50discharge ports, and recording of A4 size is performed at a head drivingfrequency of 4 kHz. In this case, scanning is performed for 72 times asshown in FIG. 11B.

In the embodiments as described above, ink is discharged by heat energyof electrothermal transducer, etc., but the discharge energy generationmeans is not limited thereto, as a matter of course.

As is apparent from the above description, the recording regions of eachrecording head in one scanning are divided.

By this, it becomes possible to perform recording corresponding to paperfeeding and the respective recording regions per one scanning.

As the result, overlapping recording with time intervals can be donewithout lowering the recording speed as a whole, whereby not only imagequality deterioration such as overlapping recording can be prevented,but also it has become possible to correspond to a diversity ofrecording media.

In the embodiments as described above, description has been made aboutthe recording method and the recording device by utilizing the advantageof multi-head nozzle to the maximum by changing the arrangements of aplural number of recording heads. In the latter half of the followingembodiments, other than the modification examples of the aboveembodiments, the device, the recording method which can obtain theeffects of the present invention while using the ordinary arrangement ofa plural number of recording heads are to be described. The followingembodiments have the merit of accomplishing miniaturization of recordingheads than the previous embodiments.

FIG. 12 is a side sectional view showing the principal part of the inkjet recording device according to the fourth embodiment of the presentinvention.

In FIG. 12, description of the same constitutions as in FIG. 1 isredundant and hence omitted here. In the following, only thecharacteristic constitutions are to be described.

FIG. 12 has recording heads 1 to 4 mounted on a carriage in parallel tothe scanning direction as shown in FIG. 14. Also, to the recording heads1 to 4 is connected the control portion shown in FIG. 13.

FIG. 13 is a block diagram showing the recording control in the ink jetrecording device 20 shown in FIG. 12. In the same FIG., 5A is thecarriage motor for driving the carriage 5 through a carriage drivingmechanism such as belt, pulley, etc., and 200 is the head driver forgenerating discharge signals for the respective discharge ports based onthe recording data supplied from the control section. 300 is the paperfeeding driving section for driving the conveying roller 9 and the belt11, and the paper discharge roller pair 16.

The control section 7 shown in the Figure has CPU100 which practicesprocessing according to control of the device while performing givingand receiving of the data between the host device or the respectivesections of the recording device, RAM100A which becomes the work area inprocessing of CPU100, and ROM100B which memorizes the processingprocedure such as recording actuation, etc. as shown in FIG. 14A andFIG. 14B.

FIGS. 14A and 14B are diagrams for illustration of the recording methodin the embodiment shown in FIG. 12. In FIG. 14A, the recording heads 1to 4 for discharging respectively the inks of the respective colors ofR, G, B and K are supported and fixed on the carriage 5 so that therespective recording regions by scanning of the carriage 5 may becomethe same. In the same Figure, the discharge port arrays 12 to 15 cannotbe seen as they are, but for convenience of description, they are shownas perspective from above.

The recording heads 1 to 4 perform recording on a recording medium bydischarging ink through the discharge ports 12 to 15 corresponding tothe recording signals inputted as synchronized with the movement of thecarriage 5.

In this embodiment, printing is performed with the discharge port arrays12 to 15 each divided into four recording regions. The four recordingregions (1) (4) have the width of the width L of the discharge portarray equally divided into 4, and constituted so that recording may beperformed only with one head in each recording region. The recordingregion (1) performs recording with the use of the L/4 width on the paperfeeding side of the head 4 of K ink, the recording region (2) with thehead 3 of B ink, the recording region (3) with the head 2 of G ink, andthe recording region (4) with the L/4 width on the paper discharge sideof the head 1 of R ink. The recording medium 8 is recorded in the orderof K, B, G, R while being conveyed for every scanning of the carriage 5with the same width of the recording regions equally divided by theconveying roller pair 9 and the adsorption conveying belt 11. FIG. 14Bshows only the recording signals corresponding to the recording regionsas described above. Also, in the portions not corresponding to therecording regions of the respective heads, 0 is inputted as thenon-recording signal.

Based on the above constitution, in the first scanning, recording isdone corresponding to the recording signal K1 (signal corresponding toL/4 width) with the head 4 of K ink. Then, paper feeding of L/4 width isdone, and the portion where recording of the signal K1 is done in thefirst scanning proceeds to the recording region (2) and is recordedoverlappingly by the recording signal B1 (B component on the same lineas K1) with the head 3 of B ink. At the same time, recording of therecording signal K2 (K component of the line subsequent to K1) is donewith the head of the recording region (1). After the second scanning,the recording medium, after paper feeding of L/4 width, transfers to thethird scanning. In the third scanning, recording of K3, B2, G1 ispracticed in the respective recording regions similarly. Further, in thefourth scanning, recording of K4, B3, G2, R2 is practiced, and on thefirst line of the recording medium is formed a color image according tothe recording signals of K1, B1, G1, R1. Thus, by carriage scanning(color recording in response to recording signals) and paper feeding ofL/4, color images are successively formed.

In this embodiment, since the recording region is divided into 4,scanning corresponding to 3 times becomes necessary as superfluousscanning as compared with the prior art. After completion of allscanning, the recording medium 8 is discharged out of the machine by thepaper discharge roller pair 16. The function of the paper dischargeroller 16 is stabilization (aiding of adsorption conveying belt,protection of unnecessary force applied from outside of the machine) ofthe recording medium at the recording section and discharging of theterminal end.

Now, as shown in FIG. 4, FIG. 5, depending on the recording medium, theamount of ink absorbes differs greatly. Accordingly, it is preferable tochange the amount of ink discharge according to the recording medium.This has not been done at all in the prior art. In the presentinvention, from this experiment, the ratio of divided use of therecording heads is determined so that the ink amount which can berecorded within a short time may become 20 nl/mm² or less in thenon-coated paper and 25 nl/mm² or less in the coated paper.

To describe again, the absorption of ink onto paper, as shown in FIG. 6Amay be considered to be effected in the order of contact, collision, dotformation, permeation, drying. As shown in FIG. 4, in the case of thenon-coated paper, in a time of 0.2 S or shorter, no ink of 11 to 12nl/mm² or more can be absorbed and therefore, ink is discharged in anamount smaller than this range. Accordingly, in the present invention,such problem can be prevented that the ink will be overflowed and, asshown in FIG. 6B, the overflowed ink is attracted to the adjacent inkwhich has reached previously onto the paper, whereby blotting occurs atthe boundary portion.

In short, in the present embodiment, since head scanning is performedsuccessively with the recording regions for the respective heads beingadequately separated depending on the recording medium in one scanning,blotting at the boundary portion as shown in FIG. 7 can be reduced togreat extent.

For verifying the effect of this embodiment, the recording test wasperformed under the conditions shown below and consequently goodrecorded images little blotting at the boundary portion could beobtained. In contrast, when recording was performed simultaneously withthe arrangement of heads being constituted so that the respective headrecording regions were over-lapped with each other as in the ink jetrecording device in the prior art, images which were entirelypractically useless were obtained.

To describe in detail, this embodiment can perform recording of 7 colorsby use of 4 colors of R, G, B, K, and recording was performed on arecording medium of A4 size at a recording density of 360 DPI and adriving frequency of 5.4 kHz. For this recording medium, a two-foldpaper on which the diameter of the ink droplet emitted is expanded to2-fold is used.

In this case, because the recording density is 360 DPI, the pictureelement size becomes 70.56 μm square, and the dot diameter embedding thepicture element as a whole becomes 100 μm. Accordingly, the dropletdiameter emitted onto the 2-fold paper becomes 50 μm, namely its volumebecomes 65.5 pl.

When recording is performed under such conditions, the plane density ofmono-color (one discharge) becomes 13.2 nl/mm², and the plane density oftwo colors (two discharges) becomes 26.3 nl/mm², and when two colors areoverlapped or adjoined at the same time as shown in FIG. 5, the imagebecomes bad.

Also, as in the constitution of the prior art shown in FIGS. 15A and15B, when recording is performed without dividing the recording regionso that paper feeding may be performed per every carriage scanning for 4times, because the recording medium 8 contacts the paper dischargeroller pair 16 immediately after ink emission of the fourth color, imagedisturbance will occur by the contact onto the paper discharge roller.For this reason, as shown by the broken line in FIG. 12, it becomesnecessary to constitute the paper discharge roller pair with the width Lof the discharge port array or longer apart from the recording section,whereby the device becomes enlarged and also the aiding effect for theconveying belt 11 (stabilization of the recording medium) is alsolowered to make it necessary to expand the opposed distance between thehead and the recording medium, resulting in deterioration of theshooting precision of ink.

In contrast, since this embodiment is a constitution such that therecording medium reaches the paper discharge roller after scanning for 3times on completion of all recording of the first portion, the imagefixing is stabilized during this period and no image disturbance willoccur.

Also, for example, in the case of recording only of K ink, recording maybe performed in the whole head region, and paper feeding may be donewith L width, whereby the recording speed can be made greater in thecase of mono-color recording.

In the case when the recording medium is a transparent film formed ofPET or PET coated with an water absorptive material, the presentembodiment is also effective.

Also, the present embodiment is effective for obtaining recording ofhigher image quality even in the case of a recording medium having inkabsorptivity such as the coated paper.

Further, even in the case of performing mono-color recording with onemulti-nozzle head, there is the effect in making the image qualityhigher similarly as in the present embodiment. That is, by use of a headwith discharge amount set small so that the same picture element may beformed with two ink droplets, by recording ink of the same color withdivided nozzles, the image deterioration by connection of the ink in thenozzle array direction can be reduced. Thus, the emission of ink of thesame color divided each into 6.6 nl/mm², with the droplet volume beingmade about half under the same conditions as in the present embodiment,further higher image quality can be accomplished. Also, with thedischarge amount being made the same as in the present embodiment, byemission of link of the same color in double amount without blotting,high density recording becomes possible.

FIG. 16 is a perspective view showing the fifth embodiment of thepresent invention, and this embodiment has a constitution of recordingheads corresponding to recording of full color. That is, it hasrecording heads 1A, 2A, 3A and 4A corresponding to the respective colorsor yellow (Y), magenta (M), black (K) and cyan (C).

Each of these recording heads has 128 discharge ports arrayed in thesub-scanning direction. Also, it is a recording head of the cartridgetype which constitutes integrally the ink tanks of the respectivecolors, and therefore when there is no more ink, the whole recordinghead is exchanged with another cartridge.

When high resolution recording is performed as in this embodiment, thepositional precision between the heads is required to be higher, and byexchange of the head with 4 colors integrated as in the head of thisembodiment, it becomes possible to effect strict registration duringshipment, and even in a device of the head exchange system, high imagequality recording extracting fully the performance of the head isrendered possible.

FIGS. 17A and 17B are conceptional views showing the recording method bythe recording head shown in FIG. 16 which are similar to FIGS. 14A and14B, respectively.

This embodiment shows the constitution in which recording at a recordingdensity of 600 DPI is performed on a 2-fold paper. Thus, since therecording density if 600 DPI, the picture element size 42.33 μm isdetermined, and similarly as described above, the droplet diamter become30 μm and its volume 14.2 pl.

As the result, the plane density when mono-color, 2 colors, 3 colors and4 colors are emitted overlappingly or adjoiningly become respectively7.9 nl/mm², 15.8 nl/mm² 23.7 nl/mm² and 31.6 nl/mm². Again, as isapparent from FIG. 5, the permissible range where no blotting or inkoccurs in this embodiment is up to 2 colors.

Accordingly, as shown in FIG. 17A, it becomes possible that therecording heads corresponding to 2 colors make the recording regions thesame. That is, the recording heads 2A and 4A of M ink and C ink have thesame recording regions as the recording heads 1A and 3A of Y ink and Kink, respectively, and recording of A3 size is performed by scanning for153 times in the data mode as shown in FIG. 17B.

FIG. 18 is a perspective view of an ink jet recording device which canmount the recording heads shown in FIG. 16 and FIG. 17, and the carriage5 is engaged slidably with a pair of guide shafts, and makes scanning ofthe recording regions with the recording heads 1A, 2A, 3A, 4A possibleby driving of the carriage motor 5A.

Thus, the number of the recording regions divided can be set as desired,and this setting is done by varying the paper feeding amount and therecording signal supplied to the recording heads in the controlconstitution shown in FIG. 13. By doing so, the method can correspond torecording media inferior in ink absorption characteristic, such as plainpaper or transparent paper for OHP, whereby recording media can bediversified.

Among plain papers, some are also poor in color formability of ink, andit may be sometimes necessary to increase the density, particularly inthe case of recording with a mono-color ink. In this case, for example,the discharge ports of the recording head of K ink are divided into two,and the same recording as in the constitution shown in FIG. 17A ispractices. The recording signals at this time are shown below.

Head scanning 1 2 3 . . . 150 151 152 153

K(2) region 0 K₁ K₂ . . . K₁₄₉ K₁₅₀ K₁₅₁ K₁₅₂

K(1) region K₁ K₂ K₃ . . . K₁₅₀ K₁₅₁ K₁₅₂ 0

According to this embodiment, it becomes possible to diversify therecording media by diversifying of the recording mode. Also, althoughimage deterioration through the difference in shooting precision,discharged amount, etc. existing between the discharge ports isintensified by overlapping recording with the same ports, it will not beintensified in overlapping recording by use of divided discharge ports,but alleviated in most cases.

FIG. 19 is a conceptional view of the recording method according to theseventh embodiment of the present invention.

This embodiment has a constitution tekan in the case of low recordingdensity, and in this case, because the ink density of mono-color becomeshigher, the possibility of blotting between the scanning lines becomeshigher.

The recording medium to be used in this embodiment is a film fortransmission type OHP, and in this case, since the projected lighttransmits the transparent film only once, and therefore absorption withthe dye becomes smaller, whereby contrast of the projected image can beobtained with difficulty. For this reason, a thick ink receptive layer(opaque) is provided on a film such as PET, etc., whereby inkabsorptivity can be improved, and therefore. by performing recordingwith 4 divided recording regions, recording of high density withoutblotting becomes possible.

For recording in this embodiment, inks of two colors of R and K wereemployed, and two heads having 50 discharge ports were arrayed in thescanning direction. Recording of A4 size was performed at a recordingdensity 300 DPI and a driving frequency of 4kHz.

As the result, the picture element size became 84.67 μm square, thepicture element dot diameter 120 nm, the droplet diameter 60 nm, thedroplet volume 113 pl, the mono-color ink plane density 15.8 nl/mm², andtwo-color ink plane density 31.6 nl/mm².

The recording signals in the recording method shown in FIG. 19 are shownin the following Table.

Head scanning 1 2 3 4 5 6 7 8 9 . . .

K(4) region 0 0 0 0 0 0 0 0 0 . . .

K(3) region 0 0 K1 K2 K3 K4 K5 K6 K7 . . .

K(2) region 0 0 0 0 0 0 0 0 0 . . .

K(1) region K1 K2 K3 K4 K5 K6 K7 K8 K9 . . .

K(4) region 0 0 0 R1 R2 R3 R4 R5 R6 . . .

K(3) region 0 0 0 0 0 0 0 0 0 . . .

K(2) region 0 R1 R2 R3 R4 R5 R6 R7 R8 . . .

K(1) region 0 0 0 0 0 0 0 0 0 . . .

As described above, when overlapping recording is performed with inks ofplural colors, the emission amount of inks will become very high indensity, and therefore in the system as in the prior art whereinrecording of the next line is commenced with paper feeding per everycompletion of scanning for plural times, the difference in ink receptiveamount between the lines becomes greater. As the result, imagedeterioration (density nonuniformity) of the joint which may beconsidered to be caused to the change in absorption phenomenon of ink ofthe next line is liable to be generated at the boundary portion betweenscanning lines, whereby blotting of the previous line toward the paperfeeding direction is great.

In contrasts, in the seventh embodiment as described above, since theink receptive amount changes gradually per every line, such troublebecomes little.

Also, as the problem caused by increase of ink amount, there maysometimes occur waving phenomenon of paper due to swelling, stretchingand shrinkage by ink reception of the paper, but in the presentembodiment, since the region which has become to have the maximum inkdensity within the same time has become smaller as compared with theprior art example as described above, there is also the effect thatwaving is suppressed.

Accordingly, it is not necessary to expand specially the intervalbetween the head and the recording medium, whereby shooting precision ismore excellent than the prior art example to improve image quality.

As is apparent from the above description, according to the pluralnumber of recording heads, recording medium is conveyed with only thewidth of the recording divided in every one scanning, and recording isperformed only with the predetermined discharge ports corresponding tothe recording regions in response to such conveyance.

As the result, as compared with separate recording for the respectivecolors with the whole head width without division of the recordingregion, the ink emission region or one scanning can be made narrowersubstantially without increasing the scanning times, and thereforecockling which is the waving phenomenon of recording medium can be madelittle. Also, since the paper discharge portion can be made shorter,miniaturization of the main body has been rendered possible.

Further, as compared with overlapping recording of the recording regionover the whole head width, the width of the region reaching the maximumdensity at the same time can be made narrower substantially withoutincreasing the scanning times, and therefore cockling can be madelittle, and also the difference in ink receiving ability during emissionbetween the scanning lines can be made little, whereby the densityuniformity at the line boundary portion has become better. Also, sinceoverlapping emissions are done through separate discharge ports, thedensity irregularity due to the difference in discharge port precisionis alleviated. Also, in performing overlapping recording, the recordingtime can be reduced, and otherwise the joint between the images can bemade better.

Further, in addition, a desirable diversity of recording can be providedto users, whereby it has become possible to perform good recording on adiversity of recording media.

FIG. 20 shows the basic schematic view of the device for obtaining theoptimum recording speed improvement ratio after having obtained higherdensity or higher image quality by partial use of the respective headsof the present invention.

400 is a means for detecting automatically or manually the material ofthe recording medium (difference in materials, including paper or resinsheet or converted paper, semiconverted paper, those with great inkabsorption amount, plain paper A, B, C: see FIG. 21), and as theautomatic discrimination, various known discrimination methods such aslight transmission, attachment of different marks according to therespective materials and discrimination thereof, etc. can be utilized.500 is a means for determining the number for the total number M of thedischarge ports of each recording head, and in this embodiment, thedivided ratio n of the total number M is determined in the presentembodiment. Specifically, the means 500 has determined which one of thegroups G1 to G8 (G1 to G8 are groups each having 8 discharge ports)suited for recording of the recording heads 1, 2, 3, 4 suitable for thematerial of the recording material should be used. According to thespecific example of the present embodiment, also by referring to FIG.21, the ink absorption amount is large to the extent which requires nodivided uses for converted paper with large ink absorption amount, andtherefore no divided driving may be practiced, but recording speed willbe thereby lowered. For this reason, for utilizing the effect of thepresent invention, n may be preferably 2 or more. For the ratio n, withthe discrimination result of semi-converted paper, plain paper A, n=2 isemployed, and recording of the embodiment shown in FIGS. 17A, 17B asdescribed above is practiced. On the other hand, with the discriminationresult of plain paper B, n=4 is employed, and recording of theembodiment shown in FIG. 19 is practiced. Further, for plain paper C orOHP sheet, n=8 is employed, and group G1 units with one scanning widthof discharge ports 8 are practiced as in the above-mentioned embodiment.

600 is a recording head driving means, and the recording signalimparting regions which are the discharge ports to be used for therecording heads 1, 2, 3, 4 are determined and driven on the basis of theratio n determined by the above-mentioned determining means 500. 700 isa recording medium conveying means, and for the printable regions x atall the discharge ports of the recording head, the conveying amount x/nof one scanning unit is determined on the basic of the ratio ndetermined by the determining means 500, and the pitch with respect tothe recording medium conveying direction which is the sub-scanning inthe recording mode determined is continued to be delivered each by x/n.

With the constitution shown in FIG. 20, regardless of the kind of therecording medium, ink jet recording of good quality and high speed canbe surely performed.

FIG. 21 shows the display panel 800 by which the operator determines thedivision ratio n for conveying the abovementioned recording headscorresponding to the recording medium to be employed. 801 is the key forconverted paper, and by turning on the key, the recording mode describedin FIG. 21 is set. Similarly, 802 is the key for semi-converted paper,plain paper A, 803 the key for plain paper B, and 804 the key for plainpaper C or sheet for OHP. 805 displays the total discharge port number Mof the recording head, and in this embodiment represents 64. 806displays during print or the print switch of operation.

Even if the constitution may be made as shown in the operational panelof FIG. 21 in which the operator can simply determine and employ therecording mode of the present invention, the effects of the presentinvention can be fully obtained. The all discharge port utilization modeof the key 801 is not required in practice as a matter of course, butmay be also provided for practicing various kinds of recording systems.

The numerical values in the foregoing embodiments are not of courselimiting conditions for the present invention, and the precision of thepresent invention is enough even if the number of discharge ports to beused may be determined without determination of the ratio of the totalnumber of discharge ports.

The present invention brings about excellent effects particularly inrecording heads, recording devices of the bubble jet system among theink jet recording systems.

Its representative constitutions and principles should be preferablythose by use of the basic principle disclosed in U.S. Pat. Nos.4,723,129 and 4,740,796. This system is applicable to either of the socalled on-demand type and continuous type, but particularly in the caseof the on-demand type, it is effective, because by applying at least onedriving signal which gives abrupt temperature elevation exceedingnuclear boiling to the electrothermal transducers arranged correspondingto the sheets or liquid passages on which liquid (ink) is held, heatenergy can be generated in the electrothermal transducers to effect filmboiling on the heat-acting surface of the recording head, andconsequently form bubbles within the liquid (ink) corresponding one byone to the driving signal. Even if the liquid (ink) may be dischargedthrough opening for discharge by growth, shrinkage of the bubbles, atleast one droplet will be formed. By making the driving signal shaped inpulse, instantly growth and shrinkage of the bubble are effectedadequately, whereby discharge of liquid (ink) particularly excellent inresponse characteristic can be more preferably accomplished. As thepulse-shaped driving signal, those as described in U.S. Pat. Nos.4,463,359 and 4,345,262 are suitable. Further recording can be performedby employment of the conditions disclosed in U.S. Pat. No. 4,313,124concerning the temperature elevation ratio of the above-mentionedheat-acting surface.

As the constitution of the recording head, in addition to the combinedconstitution of discharge port, liquid passage, electrothermaltransducer as disclosed in the respective specifications as mentionedabove (linear liquid passage or right angle liquid passage), theconstitutions by use of U.S. Pat. Nos. 4,558,333 and 4,459,600disclosing the constitution in which the heat-acting portion is arrangedin a flexed region are also included within the present invention. Inaddition, the present invention is also effective even if theconstitution may be made one based on the constitution disclosed inJapanese Laid-Open Patent Application No. 59-123670 which discloses theconstitution comprising a slit common to a plural number ofelectrothermal transducers as the discharge portion of theelectrothermal transducers or the constitution Japanese Laid-Open PatentApplication No. 59-138461 which discloses the constitution comprisingopening for absorbing the pressure wave of heat energy corresponding tothe discharge portion.

In addition, the present invention is also effective for the case ofusing a recording head of the freely exchangeable chip type whichenables electrical connection to the main device or feeding of ink fromthe main device by mounting onto the main device, or a recording head ofthe cartridge type integrally provided on the recording head itself.

Also, addition of restoration means, preliminary aiding means, etc. tothe recording head is provided as the constitution of the recordingdevice of the present invention is preferable, because the effects ofthe present invention can be further stabilized. Specific examples ofsuch means may include, for recording heads, capping means, cleaningmeans, pressurization or suction means, preliminary heating means suchas electrothermal transducer or heating element separate from this orcombination of these, and it is also effective for performing stablerecording to practice a preliminary discharge mode which performsdischarging separately from recording.

Further, as the recording mode of the recording device, not only therecording mode only of the main color such as black, etc., but also therecording head can be constituted integrally or according to acombination of plural number, and the present invention is extremelyeffective also for a device equipped with at least one of complex colorswith different colors or full colors by color mixing.

The present invention can solve adequately the various problems found bythe present inventors according to the constitution, driving not foundin the prior art, and is an industrially effective invention.

What is claimed is:
 1. An ink jet recording device comprising:arecording head having one array of ink discharge ports for emitting oneink and another array of ink discharge ports arranged for emittinganother ink, wherein said one ink and said another ink are of differentcolors, and the ink discharge ports are arranged in an arrangementdirection; a main scanning means for moving, in a direction differentfrom the arrangement direction of said ink discharge ports, saidrecording head relative to a recording medium for a main scanning duringan emission of the inks by said recording head; and a subsidiaryscanning means for moving said recording head relative to said recordingmedium by a predetermined subsidiary scanning distance during anon-ink-emission by said recording head, wherein said one array isarranged without overlapping with any of said another arrays regardingthe direction of movement of said main scanning means, and wherein saidone array and any of said another arrays of ink discharge ports arearranged with a separation between said arrays that is the predeterminedsubsidiary scanning distance in the direction by said subsidiaryscanning means so that the ink of different colors is not recorded in acontinuous main scanning.
 2. An ink jet recording device according toclaim 1, wherein said recording head further comprises a plurality ofink discharge energy generating elements, each said element comprisingan electrothermal transducer of a thermal energy generating elementwhich causes film boiling in the ink.
 3. An ink jet recording deviceaccording to either of claims 1 or 2, wherein said recording heads areintegrally formed.
 4. An ink jet recording device according to either ofclaims 1 or 2, wherein each said recording head has a recording area,and wherein said device further comprises a control means for increasinga portion covered per scanning operation by increasing the recordingarea of at least one of said recording heads, and decreasing the portioncovered per scanning operation by decreasing the recording area of atleast one of said recording heads.
 5. An ink jet recording deviceaccording to either of claims 1 or 2, wherein said recording heads areexchangeable.
 6. An ink jet recording device according to claim 3,wherein said recording heads are exchangeable.
 7. An ink jet recordingdevice according to claim 3, wherein each said recording head has arecording area, and wherein said device further comprises a controlmeans for increasing a portion covered per scanning operation byincreasing the recording area of at least one of said recording heads,and decreasing the portion covered per scanning operation by decreasingthe recording area of at least one of said recording heads.
 8. An inkjet recording device according to claim 5, wherein each said recordinghead has a recording area, and wherein said device further comprises acontrol means for increasing a portion covered per scanning operation byincreasing the recording area of at least one of said recording heads,and decreasing the portion covered per scanning operation by decreasingthe recording area of at least one of said recording heads.
 9. An inkjet recording device according to claim 1, wherein said first arraydischarges a black ink while said second array discharges a color ink.10. An ink jet recording method comprising the steps of:a recording stepfor recording using a recording head having one array of ink dischargeports for emitting one ink and another array of ink discharge portsarranged for emitting another ink, wherein said one ink and said anotherink are of different colors, and the ink discharge ports are arranged inan arrangement direction; a main scanning step for moving, in adirection different from the arrangement direction of said ink dischargeports, said recording head relative to a recording medium for a mainscanning during an emission of the inks by said recording head; and asubsidiary scanning step for moving said recording head relative to saidrecording medium by a predetermined subsidiary scanning distance duringa non-ink-emission by said recording head, wherein said one array isarranged without overlapping with any of said another arrays regardingthe direction of movement of said main scanning step, and wherein saidone array and any of said another arrays of ink discharge ports arearranged with a separation between said arrays that is the predeterminedsubsidiary scanning distance in the direction by said subsidiaryscanning step so that the ink of different colors is not recorded in acontinuous main scanning.
 11. An ink jet recording device according toclaim 6, wherein each said recording head has a recording area, andwherein said device further comprises a control means for increasing aportion covered per scanning operation by increasing the recording areaof at least one of said recording heads, and decreasing the portioncovered per scanning operation by decreasing the recording area of atleast one of said recording heads.